5 things to know about the Cuba 'health attacks'

At least 21 Americans have been injured by what have been described as “health attacks” that officials have theorized could be the result of sonic weapons

On Friday, the United States issued a travel warning and the State Department announced that over half of its staff would be pulling out of the American embassy in Cuba after a string of incidents that have baffled police and scientists alike.

At least 21 Americans were injured by what have been described as “health attacks” possibly caused by sonic weapons. Here are five things to know about this bizarre international crisis.

1. American diplomats are under attack – and officials have theorized the damage may be from weaponized sound.

In this Aug. 14, 2015, file photo, a U.S. flag flies at the U.S. embassy in Havana, Cuba. (AP Photo/Desmond Boylan, File)

The string of incidents affecting at least 21 Americans as well as some Canadian diplomats in Cuba dates back to almost a year ago. Although the U.S. had been hesitant to describe the victims’ health disorders as the result of attacks, that changed Friday with the announcement of the pullout.

Currently, the U.S. has not laid blame directly on Cuba, and is investigating the possible involvement of a third country in the incidents. Cuba has denied any responsibility. Officials initially theorized the incidents could be the result of a sonic weapon based on some of the victims’ accounts and the symptoms suffered after the attacks – many related to the inner ear.

2. What are the symptoms?

At the same time, part of the reason investigators and scientists are having difficulty pinpointing what is truly causing the health issue is the inconsistency in symptoms. Although inner ear problems are a common thread, the injuries suffered vary widely from victim to victim.

Some have hearing loss, some have dizziness, and others have ringing in their ears. Other reported issues include nausea, speech issues, and trouble focusing or recalling common words.

What has given investigators and experts the most pause is that some victims show signs of mild traumatic brain injury, which is unlikely to be caused by sound.

The circumstances of the attacks vary depending on the victim. Some have described a localized “blaring, grinding noise” that preceded their symptoms. Others reported “high-pitched chirping” or that they felt vibrations. Some haven’t heard any noise at all.

3. The FBI is investigating the attacks.

Despite suspicion that the attacks are the result of weaponized sound, the FBI and other investigators did not find any devices where the incidents occurred or witnessed any unusual activity via security footage of the hotspots. Federal investigators have not been able to duplicate the effects of the attacks in a lab.

4. Sound weapons exist, but nothing like this.

Further complicating the matter, no one has really seen a weapon like this before.

5. What do the experts think?

Experts say weaponized sound that could cause the range of symptoms victims have suffered in Cuba hasn’t been seen before, and isn’t likely.

Neuroscientist Seth Horowitz told Business Insider that the idea of an undetectable sonic weapon causing damage as severe as a TBI just doesn’t add up.

"There isn't an acoustic phenomenon in the world that would cause those type of symptoms," Horowitz said.

To cause that sort of damage would require a weapon easily detectible by any would-be victim, according to the report.

Dr. Toby Heys of Manchester Metropolitan University told New Scientist that of the two ways undetectable frequencies could cause serious damage, he has difficulty fitting either of them into the incidents described in Cuba. If the weapon used sound waves below the frequency of human hearing, it would require large subwoofers that would be highly noticeable.

If the weapon used sound waves at a frequency above human hearing, it would require a level of precision that also makes the attacks unlikely. The BBC reported a high frequency attack like this would also put other people in the area – including the attacker – at risk.

“Overall, I would be pretty circumspect about the claims to be honest – it is all very Philip K. Dick territory,” Heys told the New Scientist. “That said, we are living in a fairly surreal world right now.”